Illinois State Route 15 is a east-west highway in Jefferson County. It runs through the center of the county. West of Mt. Vernon, this highway was re-alinged south of the airport. The old highway in still a state highway. It is numbered in the 8000 range. IL St Rt 15 passes through the following town in Jefferson County. Mt. Vernon
IL St Rt 15 is not multi-plexed in Jefferson County. IL St Rt 15 intersects the following highways in Jefferson County. Interstate 57, at Mt. Vernon. Interstate 64, at Mt. Vernon. Illinois State Route 37, at Mt. Vernon.
A BGS on NB I-57/WB I-64. WB IL St Rt 15 in Mt Vernon.
